package day_2022_7_to_8.day48;

/**
 * @author haomin
 * @date 2022/09/02 23:20
 **/
public class Day48_9_Offer43_CountDigitOne {
    class Solution {
        public int countDigitOne(int n) {
            int digit = 1, res = 0;
            int high = n / 10, cur = n % 10, low = 0;
            while(high != 0 || cur != 0) {
                if(cur == 0) res += high * digit;
                else if(cur == 1) res += high * digit + low + 1;
                else res += (high + 1) * digit;
                low += cur * digit;
                cur = high % 10;
                high /= 10;
                digit *= 10;
            }
            return res;
        }
    }
}